Optical Path Difference Member for Focus Detection
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Solution Overview
Problem
Conventional microscope systems face challenges in securing sufficient light for image capture due to optical path difference systems, which complicates focus adjustment and reduces focus accuracy.
Innovation Solution
An image capturing apparatus with a light guiding optical system that divides the optical image into two paths, using an optical path difference producing member on the second optical path to create a difference in optical path length without dividing light, allowing for accurate focus position detection and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical path difference optical system using a half mirror and mirror is used to form an optical path difference, then focus position deviation can be detected, but light is divided and sufficient light amount for capturing a clear image cannot be secured
Solution Approach 1:
The patent extracts the optical path difference producing function from the light dividing system. Instead of using a half mirror that divides light into two paths, the invention uses a glass member that produces optical path difference while allowing all light to pass through to the imaging unit, thus securing sufficient light amount while still enabling focus position detection through contrast analysis of front and rear focused images
2Measurement precision
If the optical surface of an optical path dividing unit is inclined to adjust focus deviation direction, then focus detection becomes possible, but the optical system becomes complex and light gathering on the imaging area is reduced
Solution Approach 1:
The patent creates a virtual copy of the optical path by using a glass member that produces optical path difference, effectively copying the light path without physical inclination of optical surfaces. This allows focus deviation detection while maintaining a simple optical system configuration where the optical surface remains parallel to the imaging area
3Manufacturing precision
If conventional focus maps covering entire sample regions are used, then complete sample coverage is achieved, but processing time increases
Solution Approach 1:
The patent applies partial action by using a single imaging unit to capture only the necessary focus information for the current field of view, rather than capturing entire sample regions. The optical path difference producing member enables focus detection within the current imaging area, reducing processing time while maintaining sufficient focus accuracy for the imaged region
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables high-accuracy focus position detection and adjustment by securing sufficient light for image pickup while maintaining focus accuracy without light division, simplifying the optical path configuration.
Implementation Method 1
an optical path difference producing member which gives an optical path difference to the second optical image along an in-plane direction of the imaging area
Data Source
AI summary
In the image capturing apparatus, the optical path difference producing member is disposed on the second optical path. Thereby, the amount of light on imaging an optical image which is focused at the front of an optical image made incident into the first imaging device (front focus) and an optical image which is focused at the rear thereof (rear focus) by the second imaging device can be suppressed to secure the amount of light on image pickup by the first imaging device. Further, in the image capturing apparatus, the first imaging region and the second imaging region on the imaging area of the second imaging device are positioned on the front side of the imaging area in a scanning direction of the sample with respect to the region into which an optical image is made incident which is conjugate to the first optical image made incident into the first imaging device. Thereby, it is possible to obtain in advance a deviation direction of a focus position of the objective lens by a simple constitution.